Mix the contents of the pudding packet with the cornflour; blend to a smooth paste with a little of the milk.
Bring the remaining milk to the boil; pour it onto the pudding mixture, stirring constantly.
Return to the saucepan; cook over a low heat until the pudding boils up once.
Remove from the stove; leave to cool.
Peel and slice the bananas; add to them the lemon juice and a few grains of salt.
Turn the bananas so that they are well-coated with the lemon juice - this prevents them from becom- ing discoloured.
Place half the bananas in the baked pastry shell; pour on half of the pre- pared pudding mixture; then add the remain- ing bananas and pudding mixture.
Decorate the top with whipped cream and cherries.